Intake manifold volume

[Devildog1325]

Has anybody figured out a way to calculate this (the time it takes for the air to move from the maf sensor to the intake valve). I know most including me adjust it when we don't have data for a certain intake then work on transient tables. But is there an easier way to calculate this, it would come in handy especially with turbo setups with allot of piping. The pcm already learns the time it takes for the exhaust to exit the exhaust valve and travel to the 02 sensor and we can calculate in crank degrees when the intake valve opens. Even if this is possible and had a formula would the scanner even be fast enough to keep up? With this calculation could you then dial in the Manifold Volume.....or have I just been up too long and I'm thinking too hard?

[murfie]

Intake manifold volume is exactly that, the volume of the intake manifold, no other extra pipe or volume included. The space between throttle blade and intake valves. Transient accel/decel time refer to time the injector sprays and fuel reaches cylinder for to allow for extra/ excess fuel to compensate for a rapid change in air volume that is both increase or decrease respectively. The gain table refers to quantity of extra/excess fuel that needs to be match with expected air volume. increasing the manifold volume can help lean tip ins and lean tip outs. decreasing volume can help rich tip ins and rich tip outs. If you have rich tip ins and lean tip outs or lean tip ins and rich tip outs you wont be able to fix it with just the manifold volume. It would be fixed in the gain tables for the respective condition.

[Devildog1325]

See I've heard this explained both ways. One being from the MAF sensor to the intake valve and one being from the throttle blade to the intake valve. Example if I move the maf farther from the throttle body my fueling shouldn't change if the manifold is the same and running the same injectors? I know how to adjust these tables but I like to have a complete understanding.

[murfie]

The confusion may come from people reading this patent:

https://www.google.com/patents/US6089082

Which describes estimating air flow with the MAF inside the manifold after the TB.

Our cars operate much more like what is described in this patent:

https://www.google.com/patents/US6738706

In this patent they refer to another patent for transient conditions. https://www.google.com/patents/US5331936
you can read that for answers to what you are looking for and to why I told you The space between throttle blade and intake valves. Variable Vm in the equation.

[Devildog1325]

Thanks for the info murfie!

[mstang_man]

Air Velocity is measurement of the rate of displacement of air or gas at a specific location.

Air velocity (distance traveled per unit of time) is usually expressed in Linear Feet per Minute (LFM). By multiplying air velocity by the cross section area of a duct, you can determine the air volume flowing past a point in the duct per unit of time. Volume flow is usually measured in Cubic Feet per Minute (CFM).

this Concept of Air Velocity can also be used in air conditioning, heating and ventilating work.

[CCS86]

Has anyone else found a good method for fine tuning this?

I played with manifold volume setting to see the affect on tip in. I tried 4L, 12L, and 16L:



4L.png12L.png16L.png



There is definitely a bunch more oscillation to STFTs at 4L and 16L. I will probably test some values closer to 12L for comparison.

[BravoAlphaPerf]

Has anyone else found a good method for fine tuning this?

I played with manifold volume setting to see the affect on tip in. I tried 4L, 12L, and 16L:



4L.png12L.png16L.png



There is definitely a bunch more oscillation to STFTs at 4L and 16L. I will probably test some values closer to 12L for comparison.

As far as I've been told and gathered; the intake volume in a constant unless a physical change to the intake manifold is done, as its a physical measurement. (Like combustion chamber size, stroke, etc)

I know you've mentioned a DOB kit on your car, I'd email Jason@DOB for a manifold volume or take a peek at a 5.4 gt500 and see what they have for intake mani volume.
FWIW 15+ Roush Supercharged applications use the stock manifold volume size.

[CCS86]

As far as I've been told and gathered; the intake volume in a constant unless a physical change to the intake manifold is done, as its a physical measurement. (Like combustion chamber size, stroke, etc)

I know you've mentioned a DOB kit on your car, I'd email Jason@DOB for a manifold volume or take a peek at a 5.4 gt500 and see what they have for intake mani volume.
FWIW 15+ Roush Supercharged applications use the stock manifold volume size.

There seem to be conflicting opinions on whether that value represents the volume between the MAF and the intake valve, or the throttle body and the intake valve.

To me, I don't see how the volume of all the intake ports matters. 7/8 intake ports aren't in the flow path of any one combustion event.

Either way, the manifold itself, the intercooler, the blower and the elbow (maybe TB and intake tube) can affect the transient airflow response. It not practical to fill all this stuff with water to calculate the volume, especially when we don't know what to measure.

There will be some optimal value, where going higher or lower nets a worse fueling response. The '13 GT500 tune shows a volume of 16.83L, '11 GT500 = 15.94L . My car obviously doesn't behave well with those values.

What I am also curious about, is whether this value gets used with the Transient Accel / Decel Gain tables, or whether they function independently.

[MMGT1]

What I've done twice now, and will do again this weekend, is fill the intake that is coming off with water and measure volume. Then, new intake same procedure. Add difference to existing value and go from there. With older 4.6L when even adding a throttle body spacer in truck applications, I'll calculate the volume of the spacer and add it to manifold volume. Seems to work for me. There's probably a more "technical way" of doing it, but better than nothing, imo.

[BravoAlphaPerf]

What I've done twice now, and will do again this weekend, is fill the intake that is coming off with water and measure volume. Then, new intake same procedure. Add difference to existing value and go from there. With older 4.6L when even adding a throttle body spacer in truck applications, I'll calculate the volume of the spacer and add it to manifold volume. Seems to work for me. There's probably a more "technical way" of doing it, but better than nothing, imo.

Exactly what I have done in the past.



@CCS86-

Again, I'd talk to Jason@DOB or Lund as I know they have handled tuning a few DOB kits.

Correct. The Intake volume is used as an input into the transient fueling model. I do believe it gets used with the Transient Accel / Decel Gain Tables

Have you tried using your stock intake manifold volume? I only ask because Roush uses the same as stock on the s550 (11.96L), but the Decel Gain at startup, Accel Gain, Accel Gain at startup were slightly adjusted.
Is your stock volume close to 12?

Edit: If you have your stock manifold handy, you can fill it and test if the volume matches your stock value, thus determine if its TB to Valve or MAF to Valve, I have a feeling it is TB to Valve.

[CCS86]

I went through nearly 20 tune revisions with Lund struggling with bad throttle response, stalling, and big transient fuel swings. By the end, after finally switching away from the Roush OS, the throttle response was better, but still had big fuel swings and stalling. No magic bullet there.

Do you have any other relevant tune files for Ford Racing SC kits, Roush, etc? Just curious to compare values across similar platforms.

I do actually have a stock manifold in the garage that I could measure. Stock value is 11.1 L.

I'm wondering if modifying the manifold volume, without modifying the gain tables is a recipe for issues. I have been playing with the gain tables a little bit lately with mixed results.

[BravoAlphaPerf]

Interesting on Lund, we've had them do a few with good results...Was it Sr. or Jr.? or another guy?

Anyway, to answer your question; 2013 Cobra Jet (supercharged) has a manifold volume of 12.90L, 2014 Roush Supercharged is 11.5L, 2015 stock 11.96L, 2018 is 12.5L.... thats all i have at the moment, but there are a few in the repository and across the forum. Take a peek at a stock file vs the 14 Roush file in the repo, see if those gain tables along with the volume was changed, that might be the key for you. I've had good luck with the Roush OS, granted on 15+. Haven't messed with the older Copperheads.

I'd try leaving it close to stock or the Roush volume, then adjust the tables i listed above maybe to fine tune?

or pull your DOB manifold and measure the apprx volume, then add the difference to the stock volume for the final value as MMGT1 said above

Definitely let me know either way, I'm curious.

[sgtbilko]

I like the question. Guessing that measuring it will involve the MAF, as the throttle doesn't have any air sensor. When ya figure it out, take into account the air mass between the throttle plate and the MAF; figure that in, accounting for when the blade is open and shut, as the air timing will be different on both sides of the throttle cracker. It gets way complicated but I'm guessing you're into that, so share your learning...lol

Has anybody figured out a way to calculate this (the time it takes for the air to move from the maf sensor to the intake valve). I know most including me adjust it when we don't have data for a certain intake then work on transient tables. But is there an easier way to calculate this, it would come in handy especially with turbo setups with allot of piping. The pcm already learns the time it takes for the exhaust to exit the exhaust valve and travel to the 02 sensor and we can calculate in crank degrees when the intake valve opens. Even if this is possible and had a formula would the scanner even be fast enough to keep up? With this calculation could you then dial in the Manifold Volume.....or have I just been up too long and I'm thinking too hard?